Pentax AF220T is a clip-on type, series-controlled TTL auto flash, specially designed for use with a camera incorporated TTL flash control device. It has a guide number of 22 (ISO 100m) and covers a picture area of a 35mm lens. The color temperature is equivalent to daylight and the TTL flash range is 0.7m - 5.5m (2.3 - 18ft). It has an aperture auto set function with any Pentax programmed AE with its lens set to “A”. The usable film speed is ISO 25 - 1600 and the power source is four AA-size batteries (1.5V 4); Alkaline, Manganese, or Ni-Cd batteries. The number of flashes and recycling time (approx.) is as follows: